public class Example4_19 {
   public static void main(String args[]) {
    Student zhang = new Student();
    Student geng = new Student();
    zhang.setAge(23);
    System.out.println("zhang的年龄:"+zhang.getAge());
    geng.setAge(25);
    //zhang.age = 23;或geng.age = 25;都是非法的，因为zhang和geng已经不在Student类    //中
    System.out.println("geng的年龄:"+geng.getAge());
   }
}
